Over the past years it has been discovered that the population of extra-solar planets is large and diverse.

More than 5,000 exoplanets have been found over the past couple of decades. These exoplanets show a tremendous diversity, ranging from scorching hot Jupiters, common super-Earths, to widely separated super-Jupiters on the planet/brown dwarf boundary.

This thesis describes the implementation and on-sky demonstration of high-resolution integral-field spectroscopy for extreme adaptive optics systems that are used to find and characterize exoplanets.

At Leiden Observatory, researchers investigate the origin of stars and their planetary systems. They detect and characterize planets around other stars, which are called exo-planets. They study how stars and planets form. And they follow molecules from interstellar clouds to nascent planet systems.…

At Leiden Observatory, researchers investigate the origin of stars and their planetary systems. They detect and characterize planets around other stars (exoplanets). They study how stars and planets form. And they follow molecules from interstellar clouds to nascent planet systems. This way they address…

This thesis describes the Multi-site All-Sky CAmeRA (MASCARA), which consists of two small robotic telescope designed to detect exoplanets around the brightest stars in the sky.

Understanding the formation and evolution of planetary systems is one of the most fundamental challenges in astronomy. To directly image and study young exoplanets and the circumstellar disks they form from, dedicated high-contrast imaging instruments are built.

The next generation of high-contrast imaging instruments on space-based observatories requires sophisticated wavefront sensing and control in addition to a high-performance coronagraph.

One of the key discoveries in exoplanet research over the past decade is the abundance of small planets in our Milky Way. Despite their high numbers, our understanding of their atmospheres remains limited, and it is unknown if they possess atmospheres at all.

One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) to which the primary adaptive optics system is inherently blind. The main focus of this thesis is the development and…

Promotores: Prof.dr. C.U. Keller, Prof.dr. H.C. Gerritsen

Promotor: C.U. Keller, Co-Promotor: F. Snik

Promotor: Christoph U. Keller, Co-promotores: Matthew A. Kenworthy, Frans Snik

This thesis describes the development and validation of new high-contrast imaging techniques, with the ultimate goal of enabling the next generation of instruments for ELT-class telescopes to directly image Earth-like extra-solar planets orbiting around nearby stars.

Dutch astronomers have measured a superstorm for the first time in the atmosphere of an exoplanet, the well-studied “hot Jupiter” HD209458b. The very high-precision observations of carbon monoxide gas show that it is streaming at enormous speed from the extremely hot day side to the cooler night side…

This thesis aims to demonstrate how the achromatic nature and design flexibility of liquid-crystal optics can be used to improve high-contrast imaging instruments to facilitate detailed exoplanet characterization.

Astronomers at Leiden University have discovered the first planets using a new instrument: the planet hunter MASCARA. This instrument, developed at Leiden Observatory, looks specifically for planet transitions around the brightest stars in the sky, which surprisingly enough have so far have hardly been…

An international team led by Leiden astronomers has, after years of searching and defying the boundaries of a telescope, for the first time directly captured polarised light from an exoplanet. From this light they can deduct that a disk of dust and gas orbits the exoplanet. In this disk moons are possibly…

An international team of scientists including Leiden's Joe Callingham has discovered nineteen red dwarf stars that unexpectedly emit radio waves. The outbursts possibly originate from interaction with exoplanets. The results of the research appear in two scientific publications.

Professor Ignas Snellen has developed an online platform where exoplanet researchers can post videos about their work: exoplanet-talks.org. ‘For young researchers in particular it’s a way to bring their research to people’s attention.’

The James Webb Space Telescope has found evidence of carbon dioxide (CO₂) in the atmosphere of a giant planet 700 light years away. This result provides insight into the composition and formation of this gas giant and shows what James Webb is capable of. The research by the international group of astronomers,…

Two Leiden scientists - Ignas Snellen and Bernhard Hommel - have been awarded an ERC Advanced Grant. The grant will fund their research over the coming five years on exoplanets and free will.

Researchers from Japan and the Netherlands who were previously involved in the discovery of an exoplanet with huge rings have now calculated that the giant rings may persist more than 100,000 years, as long as the rings orbit in the opposite direction to that of the planet around the star. Their findings…

Astronomers from the Leiden Observatory and from the University of Rochester (in the US) have discovered that the planetary ring system that covered the very young sun-like star J1407 is actually of enormous proportions. In fact, it’s much larger and heavier than the ring system surrounding Saturn.…

The Netherlands Organisation for Scientific Research has awarded Leiden astronomer Giovanni Rosotti a Veni grant for research into very young exoplanets. This grant offers young researchers the possibility to develop their innovative ideas for a period of three or four years.

Promotor: Prof.dr. I.A.G. Snellen, C.U. Keller

Over the last three decades, the discovery of exoplanets has revealed the boundless variety of worlds beyond our own Solar System⁠. Majority of planetary systems contain short-period planets that are larger than Earth but smaller than Neptune⁠.

An international team of astronomers have become the first in the world to detect isotopes in the atmosphere of an exoplanet. It concerns different forms of carbon in the gaseous giant planet TYC 8998-760-1 b. The research will be published in the scientific journal Nature on Thursday.

For a number of years, two ‘boxes’ in the Canary Islands and Chile have been scouring the skies for exoplanets that orbit bright stars. PhD candidate Geert Jan Talens helped develop these ‘MASCARA’ telescopes and has made the first discoveries with them. Together with him, we answer the main questions…

Twee teams of astronomers, including from the universities of Amsterdam and Leiden, have discovered how hot gas giants are surrounded by large halos of thin helium gas, an indication that they are slowly losing their atmosphere. The helium, that was recently seen for the first time by the Hubble space…

Astronomer Frans Snik searches for extraterrestrial life. He doesn’t so much look at stars as at the ‘exoplanets’ alongside them.

Using the Dutch-led Low Frequency Array (LOFAR) radio telescope, astronomers have discovered unusual radio waves coming from the nearby red dwarf star GJ1151. The radio waves bear the tell-tale signature of aurorae caused by an interaction between a star and its planet. The radio emission from a star-planet…

To what extent does exoplanet Proxima b resemble our Earth? And is there some form of life present? Astronomers hope to find answers to these questions with the new European Extremely Large Telescope (ELT). An NWO research grant of €18 million will allow a Dutch consortium to continue building instruments…

Leiden University has participated in an international study carried out by the CARMENES consortium, which has discovered two small, terrestrial planets around Teegarden’s Star. The planets have masses similar to Earth and their temperatures could be mild enough to sustain liquid water on their surf…

This thesis addresses the chemical processes that determine the compositions of giant planet atmospheres.

Researchers using NASA’s James Webb Space Telescope may have detected atmospheric gases surrounding 55 Cancri e, a hot rocky exoplanet 41 light-years from Earth. This is the best evidence to date for the existence of any rocky planet atmosphere outside our solar system.

Promotor: I. A. G. Snellen, Co-promotor: M. A. Kenworthy

A group of astronomers led by Leiden PhD student Sebastian Zieba has discovered using the James Webb Space Telescope (JWST) that the rocky exoplanet TRAPPIST-1 c has a thin atmosphere. Although the planet is nearly identical to Venus in size and temperature, and was expected to have a thick atmosphere,…

One unravels the origin of the largest black holes in the universe, the other investigates the influence of stellar wind on the atmosphere of exoplanets. Both Elena Maria Rossi and Aline Vidotto receive a Vici grant for their research into the mysteries of the universe. ‘I have no idea yet how we can…

The night side of exoplanet WASP-43b, to the surprise of astronomers, does not appear to contain methane. It is likely that extreme winds do not allow enough time for methane to form in detectable amounts. This is the conclusion of an international team of scientists, with Leiden and Amsterdam contributions,…

An international team of astronomers has revealed the first 'chemical profile' of an exoplanet's atmosphere. The team, including Leiden astronomer Yamila Miguel and provenda Amy Louca, made the profile using so-called Early Release Science data from the James Webb Space Telescope. The results have been…

Diverse types of exoplanets such as gas giants on close-in orbits (hot Jupiters) and young massive giants on wide orbits (super Jupiters), with no analogs in the Solar System, pose challenges but also opportunities to our understanding of planet formation and evolution.

Detecting planets during their formation stages is crucial for understanding the history and diversity of fully developed planetary systems like our own. However, observing young planets directly is challenging because they are often deeply embedded within their host protoplanetary discs, rich in gas…

Even though more than 4000 extra-solar planets are known today, only a small fraction of these has been captured in an image. To better understand the planet formation mechanisms in solar-like environments we started the Young Suns Exoplanet Survey (YSES).

If there is life outside our galaxy, how could we find it? In his Oort Lecture, James Kasting talks about his search for simple life on other planets. Kasting was in the Netherlands for two weeks, because he was invited as the Oort Professor 2018.

A remarkable population of short period transiting rocky exoplanets with equilibrium temperatures on the order of 2,000 K has recently been discovered.

Promotor: Prof. dr. I. Snellen, Co-Promotor: Dr. M. Kenworthy

The new programme Synoptic Optics, funded by the NWO Domain Applied and Engineering Sciences, will develop new optical techniques. Researcher Frans Snik and Professor of Experimental Astrophysics Christoph Keller from Leiden Observatory will test novel approaches to monitor air pollution and discover…

Is there extra-terrestrial life out there? It now looks as though we can sketch out an answer to this enduring question. Leiden Observatory is helping to build new instruments to find the most promising exoplanets.

The field of exoplanet research is rapidly advancing through the development of new technology, observing techniques, and post-processing methods.